Control device for fastening strap unit

ABSTRACT

A fastening strap unit includes a frame with a mandrel and a strap connected thereto. The strap is wrapped to the mandrel, and the first end of the strap is fixed to the mandrel and a hook is connected to the second end of the strap. A shaft extends from the frame and a motor drives the shaft which drives the mandrel. A first sensing chip is connected to the second end of the strap and a second sensing chip is connected to the first end of the strap. A sensor is connected to the frame so as to detect the first sensing chip or the second sensing chip when the strap is retracted or released to its final position, and the motor is stopped.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates to a fastening strap unit, and moreparticularly, to a control device for a fastening strap unit so as toprotect the motor when the strap is released or retracted to the finalposition.

(2) Description of the Prior Art

The conventional fastening strap unit is usually used to secure anobject such as a wheelchair, machine and box, and generally comprises amandrel, a strap, an operation device and a motor. The strap is wrappedto the mandrel and can be released or retracted relative to the mandrel.The motor drives the operation device to release and retract the strap.The strap has a hook which is hooked to the object and the strap isreleased or retracted to a desired length so as to position the objectin a vehicle or a fixed object.

However, if the strap is overly released or retracted, the motor will beoverloaded to damage the power system of the unit.

The present invention intends to provide a control device for afastening strap unit and the movement of the strap automatically stopsto protect the motor.

SUMMARY OF THE INVENTION

The present invention relates to a fastening strap unit and comprises aframe having a mandrel and a strap connected thereto. The strap iswrapped to the mandrel. The strap has a first end fixed to the mandreland a hook is connected to a second end of the strap. A shaft extendsfrom the frame and a motor drives the shaft which drives the mandrel. Afirst sensing chip connected to the second end of the strap and a secondsensing chip is connected to the first end of the strap. A sensor isconnected to the frame and detects the first sensing chip or the secondsensing chip to stop the motor.

The primary object of the present invention is to provide a controldevice of a fastening strap unit, the motor is stopped when the strap isreleased or retracted to its final position, such that the motor isprotected from being overloaded.

The present invention will become more obvious from the followingdescription when taken in connection with the accompanying drawingswhich show, for purposes of illustration only, a preferred embodiment inaccordance with the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view to show the fastening strap unit of thepresent invention;

FIG. 2 is a perspective view to show the strap wrapped to the mandreland the strap has a hook and a sensing chip;

FIG. 3 is a plan view to show that the strap is retracted to themandrel;

FIG. 4 is a plan view to show the fastening strap unit of the presentinvention, and

FIG. 5 is a plan view to show that the strap is released from themandrel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1 to 5, the fastening strap unit of the presentinvention comprises a U-shaped frame 10 and a board 11 extends from twosides of the frame 10. A mandrel 12 and a strap 13 are located betweentwo sidewalls of the frame 10 and the strap 13 is wrapped to the mandrel12. The mandrel 12 is rotatably connected between the two sidewalls ofthe frame 10. The strap 13 has the first end fixed to the mandrel 12 anda hook 133 is connected to the second end of the strap 13. A firstsensing chip 131 is connected to the second end of the strap 13 and asecond sensing chip 132 is connected to the first end of the strap 13.In this embodiment, each of the first and second sensing chips 131, 132is a metal chip. A sensor 15 is connected to the frame 10 and detectsthe first sensing chip 131 or the second sensing chip 132 to stop themotor 50.

A shaft 122 co-axially connected to the mandrel and extends from theframe 10. The motor 50 drives the shaft 122 which drives the mandrel 12so as to release or retract the strap 13.

The frame 10 is fixed to a fixed object such as a vehicle by the board11, and the strap 13 is pulled to an object such as a wheelchair (notshown), the hook 133 hooks to the object and the mandrel 12 and thestrap 13 are stopped. Therefore, the object is positioned by the strap13 as shown in FIG. 3.

When retrieving the strap 13, the hook 133 is unhooked from the object,the motor 50 is activated to drive the shaft 122 and the mandrel 12 toretract the strap 13. It is noted that the user can simply pull thestrap 13 and to hook the hook 133 to the object manually. The retrievingof the strap 13 can be done by using the motor 50.

When the strap 13 is released or retracted, the sensor 15 detects thefirst sensing chip 131 or the second sensing chip 132 passing there by,and the detection sends a signal to the motor 50 to stop the motor 50.By this way, the motor 50 is stopped and protected when the strap 13 isreleased or retracted to its final position.

While we have shown and described the embodiment in accordance with thepresent invention, it should be clear to those skilled in the art thatfurther embodiments may be made without departing from the scope of thepresent invention.

What is claimed is:
 1. A fastening strap unit comprising: a frame havinga mandrel and a strap connected thereto, the strap wrapped to themandrel, the strap has a first end fixed to the mandrel and a hookconnected to a second end of the strap, a shaft extending from the frameand a motor driving the shaft which drives the mandrel, a first sensingchip connected to the second end of the strap and a second sensing chipconnected to the first end of the strap, and a sensor connected to theframe and detecting the first sensing chip or the second sensing chip tostop the motor.
 2. The unit as claimed in claim 1, wherein each of thefirst and second sensing chips is a metal chip.